The present invention relates to a booster for use with a brake system of a vehicle.
As one type of booster for use with a brake system of a vehicle, there is known an electric booster which drives an electric motor according to an operation of a brake pedal, advances a piston of a master cylinder via a rotation/linear motion conversion mechanism such as a ball and screw mechanism, and thereby generates a brake hydraulic pressure. For example, International Publication No. 2009/068404 discloses this type of electric booster. The disclosed brake booster is configured to feed back a part of a reaction force from a master cylinder during a brake operation to a brake pedal through a reaction member made of an elastic body such as rubber in a similar manner to a pneumatic booster using an intake negative pressure of an engine as a boosting source, which is adopted in many vehicles. This configuration realizes feedback of a reaction force from the master cylinder to the brake pedal with a simple structure.